Lens Question

[Dwig]

... I've heard that a portrait lens is ideally closer to 100mm?? (Is that correct?) Why is that?

No, its not. That is, unless you also specify the format of the camera. Then it might or might not be ideal.

To start with, its not the lens that's the "magic" element in good portraits. Instead, its the shooting distance. Distance alone controls perspective. We normally judge someone's face from 6-10 feet away (most prefer something toward the longer end of that range these days). To get a "normal" looking perspective (size of nose relative to size of ears, ...) you need to shoot from a similar distance. Any lens will do as long as you are the "magic" distance from your subject.

The lens that works best for portraits is the one that gives you the framing (tight face only, head & shoulders, waist up, ...) that you want when you shoot from the proper distance. For face shots and tight head & shoulders, you'll find that something around a 90-100mm lens on a full frame 35mm film camera puts you at the right distance. For other formats, the focal lenght would be different. On the common APS-c format DSLR, the "magic" FLs are in the 60-80mm range, with 50-55mm being on the short side but they work very well, particularily for looser framing. For 4/3rds, lenses around 50mm would be good choices. If you are shooting medium format roll film the lenses would necessarily be longer, 150-200mm for 6x4.5 and 6x6 or 200-250 for 6x7. With large format there are some additional factors to consider, particularily the impact of the necessary bellow extension on the lens' FOV (a head & shoulders shot on an 8x10 works out to about 1/2 life size with substantial extension from infinity).

 

[Tighearnach]

Huh? What does that mean a trade off? You can get fast lenses which deliver superior IQ ... like most everything else in life ...you get what you pay for ... and a fast lens with superior optics will cost more money than a fast lens with less than superior optics ... or a slow lens with superior optics.

If money is a consideration (as it is with most of us), look at pro-level third party lenses. Most pro-level lenses have pretty much equal IQ/resolution as Canon L lenses (Canon L lenses are better built).

If you desire a prime, look at Sigma 20mm F/1.8, 24mm F/1.8 and 28mm F/1.8. All are sharp and will focus very very close to the front element (1:4 magnification on the 20mm). They run in the neighborhood of $400.

Gary

Of course you get what you pay for. That was my point. I was pointing out that if his budget was 500US then he could go for a zoom lens as opposed to a prime. A 500 dollar prime will be faster and deliver better IQ than a 500 dollar 18-50. At least as far as i can see.........